The present invention relates generally to optical switches, and, more particularly, to an apparatus and method for directing optical signals using a movable optical switching element.
Communication technology has progressed significantly in the past few years. Today, much information is carried over optical communications fiber. This fiber optic technology allows the transport of information at data rates currently exceeding millions of bits of information per second. Part of the technology that enables this optical communication is the ability to direct light onto an optical fiber and switch that light appropriately. Typically, a number of optical fibers are combined into a fiber optic cable. When a fiber optic cable is carrying many individual signals over large distances, it is necessary to have the ability to switch those signals onto other fiber optic cables. A mesh of fiber optic cable infrastructure spans the world. At certain places in the mesh it is desirable to have the ability to switch the light signals from one fiber optic cable to another. A typical fiber optic cable may be comprised of a plurality of individual optical fibers bound together, for example, in a ribbon arrangement. A typical fiber optic ribbon cable may contain 32 individual optical fibers. Each optical fiber is capable of carrying one signal, or in the case of dense wave division multiplexing (DWDM), in which many signals may be multiplexed onto a single optical fiber through the use of multiple colors of light, each optical fiber may carry a plurality of light colors (wavelengths), with each color representing a single signal.
Optical switches capable of routing light from one direction to another have been known for some time. One type of optical switch element is disclosed in commonly assigned U.S. Pat. No. 5,699,462 to Fouquet et al., in which an optical switch element is located at an intersection of two optical waveguides. Depending on the state of a material within the optical switch element, light is either transmitted through the switch element continuing axially on the original waveguide, or reflected by the switch element onto a waveguide that intersects the original waveguide. The switch element is filled with a material that, while in a transmissive state, has an index of refraction substantially equal to that of the waveguide, thus allowing light in the waveguide to pass through the switch element. The state of the material within the switch element may be changed, through the operation of heaters within the switch element, so as to vaporize the liquid in the switch element to form a bubble. While present in the switch element the bubble causes a refractive index mismatch between the waveguide and the switch element, thus causing the light in the waveguide to be reflected onto the intersecting waveguide. This state is known as the reflective state. The operation of a preferred and many alternative embodiments of this switch element is set forth in detail in the above-identified commonly assigned U.S. patent to Fouquet et al.
When placed at an intersection of two waveguide segments, one of the above-mentioned optical switch elements forms an optical switch point, which may be used to switch signals on a plurality of optical fibers. The optical switch points may be further arranged so as to form a switching matrix. For example, when arranged in a 32xc3x9732 matrix, formed by 32 rows and 32 columns of optical switch points, a 32 fiber optic ribbon cable can be connected to 32 input lines and another 32 fiber optic ribbon cable can be connected to 32 output lines, the output lines intersecting the 32 input lines. Because a switch element is located at each optical switch point it is possible to switch any of the 32 input lines to any of the 32 output lines. In this manner, optical signals may be directed from one fiber optic cable onto another, resulting in a compact optical switch.
Although the above-described switch element is useful in many applications, there may be situations in which the use of an optical switch that does not use fluid, and that does not require a heater to form a bubble in the fluid, may be desirable.
Therefore, an alternative manner for switching light in an optical fiber switch matrix would be desirable.
The invention provides an apparatus and method for directing optical signals using a movable optical switching element.
In architecture, the present invention may be conceptualized as an apparatus for directing optical signals. The apparatus comprises an optical input path; and a movable optical switching element aligned with the optical input path. The movable optical switching element is configured to selectively direct the optical signal from the optical input path to one of at least two optical output paths.
The present invention may also be conceptualized as a method for selectively directing optical signals. The method comprises the following steps: providing an optical input path; providing a moveable optical switching element; directing the optical signal from the optical input path to the movable optical switching element disposed in the optical input path; and using the movable optical switching element to selectively direct the optical signal to one of at least two optical output paths.
The invention has numerous advantages, a few of which are delineated, hereafter, as merely examples.
An advantage of the invention is that it allows a plurality of optical signals to be switched simultaneously.
Another advantage of the invention is that it allows a single optical signal to be extracted from an optical fiber carrying a plurality of optical signals.
Another advantage of the invention is that it can be structured not to require constant power to maintain a switched state.
Other features and advantages of the invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. These additional features and advantages are intended to be included herein within the scope of the present invention.